Useful in radiotherapy of chemotherapy 4-aziridino-1-nitroimidazol-1-yl-2,3-butanediols

ABSTRACT

A compound of formula I ##STR1## in which formula: R 1  represents hydrogen or an alkyl group; 
     R 2  -R 5  represent hydrogen, alkyl aryl, aralkyl or alkaryl group; and 
     n is 2. 
     The compounds are used as a radiation sensitizing agent or a chemopotentiating agent for administration to a patient undergoing radiation therapy or chemotherapy for the treatment of cancer.

This invention relates to compounds useful in the treatment of cancerpatients by radiotherapy or chemotherapy, to a process for theproduction of such compounds, to formulations for administration and tomethods of treating such patients.

Accordingly, the present invention comprises a compound of formula I##STR2## in which formula: R₁ represents hydrogen or an alkyl (e.g. C₁-C₆ alkyl) group;

R₂ -R₅ represent hydrogen, alkyl (e.g. C₁ -C₆ alkyl), aryl, aralkyl oralkaryl group; and

n is 1 or 2.

In compounds I, the nitro group is typically located at the 2-positionon the imidazole ring and R₁, when an alkyl group, e.g. a methyl group,is usually disposed at the 5-position. Generally, at least two of R₂ -R₅are hydrogen and preferably at least one of R₂ -R₅ is an alkyl, e.g. amethyl, ethyl or isopropyl group or a benzyl group. Compounds whereinthe group --NO₂ is located at the 2-position, R₁ represents hydrogen, nis 1 and R₂, R₃, R₄ and R₅ represent hydrogen or R₂ and R₃ representmethyl and R₄ and R₅ represent hydrogen or R₂ and R₄ represent methyland R₃ and R₅ represent hydrogen are of particular interest.

The compounds are useful in increasing the sensitivity of tumour cellsto radiation in radiotherapy and also in potentiating or enhancingdamage to tumours by chemotherapeutic agents.

A compound I may be produced, in accordance with a further aspect of thepresent invention from compound II by treatment thereof with anaziridine of formula III preferably in a polar solvent such as analcohol. ##STR3##

In a second process within the scope of the present invention for theproduction of the compound I, the compound of formula II is reacted witha compound of formula IIIA:

    H.sub.2 NCR.sub.2 R.sub.3 CR.sub.4 R.sub.5 --X             IIIA

wherein X represents a halogen, typically chlorine or bromine,preferably in the presence of an acid acceptor e.g. an alkali metalhydroxide.

In a third process within the scope of the present invention for theproduction of the compound I, a compound IV ##STR4## wherein Yrepresents a halogen, typically bromine or chlorine, is reacted with anaziridine of formula III, preferably in the presence of an acid acceptore.g. an alkali metal hydroxide.

In a fourth process within the scope of the present invention for theproduction of the compound I, a compound V ##STR5## is reacted with acompound of formula VI ##STR6## preferably under neutral or basicconditions.

In a fifth alternative process within the scope of the present inventionfor the production of the compound I, a compound of formula VII:##STR7## wherein Z represents a halogen, typically bromine or chlorine,is cyclised by treatment with a base, typically an alkali metalhydroxide e.g. potassium or sodium hydroxide.

The above alternative processes are typically conducted in a polarsolvent such as an alcohol.

When n is 2, compound I may be prepared by reaction of a compound offormula VIII with an aziridine of formula III suitably in a polarsolvent such as methanol: ##STR8##

Intermediate compounds of formula VIII also form part of the presentinvention.

The compound I may be formulated in a manner appropriate to thetreatment for which it is to be used by bringing it into associationwith a pharmaceutically compatible carrier or diluent. The compound maybe included in a dosage form such as a tablet or capsule, for example acapsule comprising known formulation components such as one or more ofthose described in Example A of U.K. Patent Application No. 2003154A.The compound may also be formulated for intravenous administration e.g.in a saline drip solution.

When employed as a radiation sensitizing agent, in accordance with afurther aspect of the present invention, the compound I is administeredto a patient having a radiation sensitive cancer prior to irradiation ofsaid cancer.

The compound I may, however, in yet a further aspect of the presentinvention be employed for chemopotentiation of a chemotherapeutic agentby administration of the compound I to a patient having a localised ormetastatic cancer. Administration of the compound I is generally carriedout prior to or simultaneously with administration of thechemotherapeutic agent, for example melphalan, cyclophosphamide,5-fluorouracil or CCNU (1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea).

The invention is illustrated by the following Examples:

EXAMPLE 1 1-(2-Nitro-1-imidazolyl)-3-(1-aziridino)-2-propanol

A mixture of 1-(2,3-epoxypropyl)-2-nitroimidazole prepared by the methoddescribed by Beaman (Beaman A. G., Tautz W. and Duschinsky R., 1967;Studies in the Nitroimidazole Series, Antimicrobial Agents andChemotherapy p. 520-530), (5.10 g, 0.03 mol) and aziridine (2.60 g.,0.06 mol) in methanol (70 ml) is heated under reflux for one hour. Thereaction mixture is treated with decolourising charcoal, refluxed for 5minutes and filtered. The solvent is removed under reduced pressure to ayellow residue, which is dissolved in a minimum quantity of ethanol andallowed to crystallise to give1-(2-Nitro-1-imidazolyl)-3-(1-aziridino)-2-propanol (3.57 g, 56%, m.p.119°-121° C.) as a pale yellow crystalline solid. Recrystallizationcauses the decomposition of the product.

EXAMPLE 2 AND 3

In the following Examples, WHT mice in which the MT tumour has beenimplanted subcutaneously are administered the compound of Example 1intraperitoneally before treatment with radiation or with thechemotherapeutic agent melphalan. The time before such treatment atwhich the drug is administered is such that maximum enhancement iseffected. The results of treatment with radiation and thechemotherapeutic drug are set out respectively in Tables I and IItogether with comparison results using misonidazole (MISO) and thecompound Ro-03-8799. The asterisks against the results from treatmentwith the latter compounds indicate that the tumours treated in thesecases are intramuscular.

                  TABLE I                                                         ______________________________________                                                        MISO  8799   Compound I                                       ______________________________________                                        Example 2                                                                     Radiosensitization                                                            Administered dose 3.8     3.8    3.8                                          mmoles/kg                                                                     Enhancement ratio 1.3     1.3    1.7                                          Example 3                                                                     Chemosensitization (melphalan)                                                Administered dose  0.72    0.72  --                                           mmoles/kg                                                                     Enhancement ratio  1.7*    2.2*  --                                           Administered dose --       0.72   0.08                                        mmoles/kg                                                                     Enhancement ratio --      1.9    3.0                                          ______________________________________                                    

EXAMPLE 4 1-(2-Nitro-1-imidazolyl)-3-(2-methyl-1-aziridino)-2-propanol

In a manner analogous to that described in Example 1 there is obtainedby reaction of 2-methyl aziridine with1-(2,3-epoxypropyl)-2-nitroimidazole after crystallization fromethanol-ether,1-(2-nitro-1-imidazolyl)-3-(2-methyl-1-aziridino)-2-propanol in the formof a pale yellow crystalline solid (3.06 g, 45%, m.p. 109°-111° C.).

EXAMPLE 5 1-(2-Nitro-1-imidazolyl)-3-(2-ethyl-1-aziridino)-2-propanol

In a manner analogous to that described in Example 1 there is obtainedby reaction of 2-ethylaziridine with1-(2,3-epoxypropyl)-2-nitroimidazole after crystallization fromethanol-ether at -70° C.,1-(2-nitro-1-imidazolyl)-3-(2-ethyl-1-aziridino)-2-propanol in the formof a pale yellow crystalline solid which changes to a yellow thick oilat room temperature; yield 65%.

EXAMPLE 6 1-(2-Nitro-1-imidazolyl)-3-(2-benzyl-1-aziridino)-2-propanol

In a manner analogous to that described in Example 1, but usingequimolar amounts of reagents, there is obtained from reaction of2-benzyl aziridine with 1-(2,3-epoxypropyl)-2-nitroimidazole aftercolumn chromatography using silica gel as adsorbent,1-(2-nitro-1-imidazolyl)-3-(2-benzyl-1-aziridino)-2-propanol in the formof a pale yellow gum, in 72% yield.

EXAMPLE 71-(2-Nitro-1-imidazolyl)-3-(2,2-dimethyl-1-aziridino)-2-propanol

In a manner analogous to that described in Example 1, there is obtainedfrom reaction of 2,2-dimethyl aziridine with1-(2,3-epoxypropyl)-2-nitroimidazole after crystallization fromethanolether,1-(2-nitro-1-imidazolyl)-3-(2,2-dimethyl-1-aziridino)-2-propanol in theform of a pale yellow crystalline solid of melting point 101°-103° C.;yield 78%.

EXAMPLE 8 1-(2-Nitro-1-imidazolyl)-3-(2-phenyl-1-aziridino)-2-propanol

The compound is preparable by reaction of1-(2,3-epoxypropyl)-2-nitroimidazole with 2-phenylaziridine (K. Ichimuraand M. Ohta, Bull. Chem. Soc. Japan, 43(5) 1443-50 (1970)) in methanol,following the method described in Example 1.

EXAMPLE 91-(2-Nitro-1-imidazolyl)-3-(2-isopropyl-1-aziridino)-2-propanol

The compound is preparable by reaction of1-(2,3-epoxypropyl-2-nitroimidazole with 2-isopropylaziridine (K.Ichimura, Bull. Chem. Soc. Japan 43 1443-50 (1970)) in methanolfollowing the method described in Example 1.

EXAMPLE 10 1-(2-Nitro-1-imidazolyl)-4-(1-aziridino) or substitutedaziridino)-2,3-butane-diol. (I,R₁ =H, N=2, R₂ -R₅ =H or alkyl, aryl,aralkyl or alkaryl)

(a) 1-(2-nitroimidazolyl)-2-hydroxy-3,4-epoxy butane

3-(2-Nitroimidazolyl)-2-hydroxy-1-butene (11.83 gms, m.p. 90°-92° C.,prepared by refluxing a mixture of azomycin, 1,3-butadiene monoxide andanydrous potassium carbonate in ethanol for 5 hours) is stirredovernight in dichloroethane with m-chloroperbenzoic acid in the presenceof 3-tert-butyl-4-hydroxy-5-methylphenyl sulfide and after stirring thereaction mixture is refluxed for 1 hour. The mixture is washed withsaturated sodium carbonate solution and the aqueous phase was extractedwith chloroform. The combined dichloroethane and chloroform extracts areconcentrated to a small volume and the product is purified by columnchromatography, in which silica gel is the stationary phase and amixture of chloroform (90%) and ethanol (10%) the eluent. The product iscrystallised from ethanol as a pale yellow solid of m.p. 134°-136° C.Yield 33%.

(b) The compound from (a) is reacted with an aziridine of formula III inmethanol to yield the required compound of formula I.

EXAMPLE 11 1-(2-methyl-5-nitro-1-imidazolyl)-3-(1-aziridino orsubstituted aziridino)-2-propanol. (I,R₁ =CH₃, n=1,R₂ -R₅ =H alkyl,aryl, aralkyl or alkaryl)

1-(2,3-epoxypropyl)-2-methyl-5-nitroimidazole (M. Hoffer and E.Grunberg, J. Med. Chem. 17, 1019 (1974)) is reacted with an aziridine offormula III in methanol to yield the required compound of formula I.

EXAMPLE 12 1-(2-methyl-4-nitro-1-imidazolyl)-3-(1-aziridino orsubstituted aziridino)-2-propanol. (I,R₁ =CH₃, n=1,R₂ -R₅ =H alkyl,aryl, aralkyl or alkaryl)

The procedure of Example 11 is repeated using1-(2,3-epoxypropyl)-2-methyl-4-nitroimidazole (J. Suwinski, E. Suwinska,J. Watras (1974) and M. Widel, Acta Pol. Pharm., 15(5), 529 (1975)) toyield the required compound of formula I.

EXAMPLES 13 AND 141-(2-Nitro-1-imidazolyl)-3-(2,3-dimethyl-1-aziridino)-2-propanol (mesoand dl forms)

A mixture of meso and dl forms of 2,3-dimethylaziridine, prepared by themethod of Dickey described in J. Amer, Chem Soc. Vol. 74, p 944 (1952),is reacted with 1-(2,3-epoxypropyl)-2-nitroimidazole in a manneranalogous to that described in Example 1, to yield a mixture of the mesoand dl forms of1-(2-nitro-1-imidazolyl)-3-(2,3-dimethyl-1-aziridino)-2-propanol(isomers reflect the presence of two chiral centres in the aziridinylmoiety). The meso and dl forms are separated by column chromatography inwhich silica gel is the stationary phase and a mixture of diethyl ether(95%) and ethanol (5%) the eluant. The meso form has m.p. 84°-85° andthe dl form is isolated as a waxy solid.

Sensitisation and toxicity data for compounds described in the aboveExamples are set out in Table II.

                                      TABLE II                                    __________________________________________________________________________    Sensitisation and toxicity data on Compounds described in the Examples                                                       Therapeutic ratio.sup.d        Example Position of                            relative to Compound           number                                                                             R.sup.1                                                                          NO.sub.2 group                                                                      n R.sub.2                                                                             R.sub.3                                                                          R.sub.4                                                                          R.sub.5                                                                         C.sub.1.6 /mol dm.sup.-3.spsp.a                                                       LD.sub.50 /mmol/kg.sup.b                                                               of Example                     __________________________________________________________________________                                                   1                              1    H  2     1 H     H  H  H 1.0 × 10.sup.-4                                                                 0.61.sup.c                                                                             1                              4    H  2     1 Me    H  H  H   8 × 10.sup.-5                                                                 <0.58    <1.2                           6    H  2     1 PhCH.sub.2                                                                          H  H  H                                                 5    H  2     1 Et    H  H  H 1.3 × 10.sup.-4                                                                 0.58     0.73                           7    H  2     1 Me    Me H  H   8 × 10.sup.-5                                                                 1.25     2.56                           8    H  2     1 Ph    H  H  H   3 × 10.sup.-4                           13   H  2     1 Me(meso)                                                                            H  Me H    8 × 10.sup.-5                                                                ≦1.25                                                                           2.56                           14   H  2     1 Me(dl)                                                                              H  Me H   8 × 10.sup.-5                           10   H  2     2 H     H  H  H 1.3 × 10.sup.-4                                                                 0.41     0.52                           11   2-Me                                                                             5     1 H     H  H  H   3 × 10.sup.-4                                                                 0.80     0.44                           12   2-Me                                                                             4     1 H     H  H  H                                                 9    H  2     1                                                                                ##STR9##                                                                           H  H  H 1.3 × 10.sup.-4                                                                 ≦1.18                                                                           1.49                           __________________________________________________________________________     .sup.a Concentration required to achieve an enhancement ratio of 1.6 in       irradiated hypoxic V79 mammalian cells.                                       .sup.b Drugs administered i.p. to ♀ WHT mice.                          .sup.c For Compound of Example 1 in ♂ CRCD1 mice                         ##STR10##                                                                     ##STR11##                                                                

We claim:
 1. A compound of the formula:in which formula: R₁ represents hydrogen or alkyl; R₂ -R₅ represents hydrogen or C₁ -C₆ alkyl, or unsubstituted carbocylic aryl, aralkyl or alkaryl, wherein the alkyl moiety thereof is C₁ -C₆ alkyl; and n is
 2. 2. A compound according to claim 1 in which the nitro group is located at the 2-position in the imidazole ring.
 3. A compound according to claim 1, in which at least one of R₂ -R₅ is C₁₋₆ alkyl or benzyl.
 4. A compound according to claim 1, in which at least two of R₂ R₃ R₄ and R₅ are C₁ -C₆ alkyl.
 5. A compound according to claim 1, in which R₁ represents hydrogen.
 6. A compound according to claim 1, wherein each of R₁, R₂, R₃, R₄ and R₅ is hydrogen.
 7. A compound according to claim 1, wherein R₂, R₃, R₄ and R₅ is hydrogen, C₁₋₆ alkyl, phenyl or benzyl.
 8. A compound according to claim 2, wherein each of R₁, R₂, R₃, R₄ and R₅ is hydrogen.
 9. A pharmaceutical composition for use in radiation therapy or chemotherapy, comprising a radiation sensitizing effective amount or a chemopotentiating effective amount of a compound according to claim 1 in combination with a pharmaceutically acceptable carrier or diluent therefor.
 10. A composition according to claim 9, in which the carrier or diluent is a saline drip.
 11. A method of treating a patient having a radiation sensitive cancer, which comprises administering a radiation sensitizing effective amount of a compound of formula I according to claim 1 to the patient prior to irradiation of the cancer.
 12. A method of treating a patient having a localized or metastatic cancer, which comprises administering to the patient a chemopotentiating effective amount of a compound of formula I according to claim 1 before or simultaneously with administration of a chemotherapeutic agent.
 13. A method according to claim 12, in which the chemotherapeutic agent is melphalan, cyclophosphamide, 5-fluorouracil or 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea. 